Environment

Why Wool is Warm and Snowflakes Aren't Always Pretty

80beatsBy Veronique GreenwoodDec 27, 2011 5:16 PM

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If you live in the Northeast, chances are you've had a disappointingly balmy December so far (the snow seems to have taken a wrong turn somewhere and wound up over Texas instead

). But when the air gets that snap and you reach for the wool socks, Emily Eggleston at Scientific American has a few factoids that promise to fascinate

. Here's why wool keeps you warm:

Wool keeps out the cold because it is an excellent insulator. Crimped and crisscrossed woolen fibers create tons of little air pockets. The tiny air masses within my socks have difficulty moving in and out of the fabric. Without convective heat transfer and contact with air of other temperatures, the spaces between wool fibers maintains a steady temperature.

And why are snowflakes sometimes beautifully crystalline and sometimes clumpy as cold oatmeal?

The two main snowflake shapes are plates and columns. Plates are the typical hexagonal flakes and columns are elongated, blocky crystals. As a cloud’s temperature moves below 32º F(0º C), it will pass through various phases of crystalline potential. If enough water is present in a cloud, between 32 and 23º F (0 and -5º C), plates will form, sending small six-armed flakes to the earth. In the 23 to 14º F (-5 to -10º C) range, a cloud produces columnar snow crystals.

My own lingering question is, why does cold air have that particular smell? Is it something to do with how molecules change as they get colder? I'm off to scour the internet for an answer...

Image courtesy of Gui Seiz / flickr

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